I. Field of the Invention
This invention relates to spiral staircases and handrails therefor, more particularly to constructions for supporting a continuous handrail on posts along a staircase.
II. Description of the Prior Art
Various types of spiral staircases and the like have been shown in the past and most include a handrail associated therewith such as is shown in FIG. 1 of U.S. Pat. No. 1,031,645 to Haskell. In the past, it has been difficult to use a continuous piece of metal as the handrail for such spiral staircases because precision support pieces were require for proper alignment of the rail above the treads of the staircase. Many devices have been disclosed for securing the handrail to the treads of the staircase by balusters or posts, but all these devices suffer from the disadvantage that they require precision positioning of the handrail and precision drilling of the support and attachment mechanisms for the handrail. The alternative to this was to form screw bores and the like in the pieces on site when installing the staircase and handrail. Even in such a case, installation and fitting of the handrail was difficult and expensive. Furthermore, the attachment mechanisms were extremely complicated such as is shown by Takenaga in U.S. Pat. No. 4,132,391.
An additional problem with handrails of the prior art was that the sides of the rail were either rough or subject to being bent when formed in a manner that would facilitate attachment to balusters for support above the treads of the staircase. Attempts to form a curved spiral handrail often resulted in a crushed portion of the handrail where attachment was to be made. Thus, handrails of the prior art are conventionally formed of multiple pieces and assembled by interjoining the pieces end to end.